Electric conductor wrapping machine



Jan. 10, 1956 R. W. FINHOLT ET AL ELECTRIC CONDUCTOR WRAPPING MACHINE Filed Sept. 29, 1953 Ivventors: Robert, W F imho/t, V/'sva/d/s Abc/ins,

The/'r- Attorneg.

United States Patent i O F 2,730,474 ELECTRIC CONDUCTOR WRAPPING' MACHINE Robert W. Finholt, Lawrence Park, and Visvaldis Abolins, Eric, Pa., assignors to General Electric Company, a corporation of New York Application September 29, 1953, Serial No. 383,102 9 Claims. (Cl. 154-235) This invention relates to means for insulating conductors and has particular reference to a wrapping machine for insulating formed coil turns.

A commonly employed method of insulating conductors is to wrap them with a sheet or tape of an insulating cloth or paper-like material. This method isV commonly employed in the insulation of formed coils designed to be fitted tightly into slots in an armature or rotor of a large electric motor or generator.

The wrapping rnust in such cases be very tightly applied and hence care must be taken, especially' where the wrapping material has a low tensile strength, to prevent tearing or distortion of the wrapping material. While machines are preferably employed for holding the conductors and the wrapping material during` the wrapping process; it is similariy desirable that the machine itself be both low in cost as well as inexpensive to operate and maintain. In particular, it is very desirable that the machine be easy to disassemble and clean since particles of insulating material together with binder material often collect in' relatively large quantities according to the type of insulating material being employed.

lt is therefore an object of our invention to provide' a simple and inexpensive machine for wrapping an insulator Sheet about a conductor.

lt is a further object of our invention to provide a coil wrapping machine which tightly Wraps an insulating sheet about a coil conductor without subjecting the Sheet to undue stress.

lt is a further object of our invention to provide a coil wrapping machine which automatically applies pressure` upon the coil as it is wrapped.

Briefly, in accordance with our invention, a jig having an elongated V-shaped groove extending along its length- Wise axis holds a straight section of the conductor being wrappcd, the jig being made of non-magnetic material. A magnet positioned against the lower side of the jig with its pole pieces axially spacecl is employed to at'tract' an elongated bar made of magnetic material into the groove.

Thus, when a conductor is wrapped withV an nsulating.

sheet, the bar of magnetic material above it is forced against the conductor by the magnetic force to maintain a pressure on the conductor' and keep the wrapping tightly in place as the conductor is rotatcd.

The features ofV this invention which we believe to' be novel are set forth with particularity in the appen'ded claims. Our invention itself, however, both as to its organization and method of operation, together with further objects and advantages thereof, may best be' understood by reference to the following description taken in connection with the accompanying drawing in which Fig. l is a perspective view of a wrapping machine embodying our invention together with an armature coil being wrapped;

Fig. 2 is an end view along line 2- 2 of Fig. l;

Fig. 3 is a perspective view of another wrappingmachine embodying our invention;

Fig. 4 is an end viewV ofa modificatio'n; and

2,730,474 Patented Jan. 10, 1956 Fig. 5 is-a perspective view of a portion of another wrapping machne'representating a modification.

Referring now to Fig. 1, a wrapping machine embodying our invention is shown having a V-shaped holding jig 1 comprising an elongated plate of brass or other nonmagnetic material which is bent along a lengthwise axis to provide two planar surfaces 2 and 3 at an angle to each other, which angle may suitably be lt is these facing inner sides 2 andl 3 which define the working surfaces of the jig. Positioned against the outer surface of the jig is a horseshoe electromagnet 4 having its pole faces 5 and 6 axially spaced along the length of the jig. The pole faces are suitably grooved or cut away to accommodate the backside of the jig and bring the magnet pole pieces into close contact with it. As further shown in Figs. l and 2, each pole piece is not centered opposite the apex of the V-shaped cross section of the jig but instead more of the iron of the pole pieces is positioned against the side 3 of the jig thus concentrating the magnetic ilux on that side of the center groove of the jig. The magnet is preferably bolted to the jig, the head of each bolt 7 being fiush with an inner side of the jig and extending thercthrough and through the respective legs of the electromagnet core. A support 8, suitably comprised of brass or other non-magnetic metal rod, is brazed to the underside of one end of the jig and extends therefrom in a generally axial direction to a supporting surface such as a workbench (not shown). A winding 9 on the electromagnet is connected rnagnet leads 16 with a coil to be wrapped, they are preferably taped to the jig support rod 8 as shown on the tained within the jig when' it isv resting upon a coil turn. Due to the magnetic field established by the electromagnet when energized, the bar roller 13 is held' firmly in the V-shaped groove by magnetic attraction toward the pole faces 5 and 6 to thus exert pressure upon a conductor underneath it. It should be noted that the cylinder will apply pressure along the entire length of the jig, properly positioned by the V-block effect. While the weight of the bar roller itself provides some pressure on a coil turn within the groove, the force exerted is preferably made to be many times that due to the weight of the bar and can be remov'ed at will by opening the foot switch 12.

In operation of the machine of Figs. l and 2, a conductor assembly 14 which may suitably take the form of a group of formed -conductors comprising a turn of an armatura coil for a dynamoelectric machine is placed in the bottom of the groove of the jig. ln the examples shown in Figs. 1 and 2, this conductor group has a rectangular cross section and it is the straight portion of the to one surface of the conductor with a suitable adhesive and the conductor with the' Sheet fastened to it is placed against side 2 of'V the jig a'nd slid along that face until it restsv against they bottom of the groove formed by the junctions of' sides 2 and 3. It: is not necessary that the steel bar roller 13 be removed since it can be easily displaced upward by the entrance of the conductors providing that the switch 12 is open.

After the conductor is in place, the foot switch 12 is closed to energize the electromagnct and force the roller 13 tightly against the coil form. The coil is then rotated about its lengthwise axis to wind the insulation upon the conductors. Due to the pressure caused by the roller 13, the insulating sheet is pressed firmly and tightly against the core and the preceding insulation layers. No tension on the sheet is therefore required which is a very substantial advantage of our machine when insulating wraps of low tensile strength are employed. in the case of the rcctangular cross section coil turn shown in Figs. l and 2, it may be seen that the roller 13 not only rolls over the surface of the coil turn as the coil is rotated within jig but the roller is also displaced in dircctions transvc'rsc to its lengthurse axis. This displacement is maintained along the side 3 of the jig due to the concentration of the magnetic field on that side as mentioned in a preeeding paragraph describing the unbalanced pole piece construction. ln this way, when the partially formed coil turn 14 has a rectangular cross section departing substantiallyy from a square, the roller does not shift from side to side of the groove but instead slides or rolls along the side 3 to thus provide a steady pressure to the sheet 15 at its line of contact with the wound portion of the coil. Due to the greater distance of the roller 13 from the magnetic pole pieces when the long side of the armature turn rests against the groove side Z, the flux leakage between the pole pieces increases and the force that the roller excrts upon the coil is accordingly decreased. This, however, is generally desirable since the rectangular cross section coil turns are designed to be forced into an armature slot and must therefore have the insulation against the longer sides very tightly compressed against them while at the same time the insulation wrapping across the short sides of the conductor must not be made so tight as to unduly stress the insulating material.

As may be seen, the wrapping machine is very simple and lends itself to the wrapping of different size conductors Without adjustment of the machine. Of course, the length of the jig 1 must be as long as the length of the conductor to be wrapped and in the case of the generally Ll-shaped armature coils shown in Pig. l, the length of the jig is preferably not much greater than the straight sides of the coil in order that the coil may be adequately wrapped and that it may be rotated without obstruction.

Referring now to Fig. 3, another embodiment of a coil wrapping machine in accordance with our invention is shown therein. In this case, the V-shaped coil wrapping jig 16 has one of its sides extended bent over to provide an off-duty holder 17 for the pressure bar roller IS. Such a cross section of the jig assembly may suitably bc described as W-shaped. The V-shaped shelf portion or holder 17 is especially useful when the magnetic attraction force is provided by a permanent horseshoe magnet 19 corresponding in position and function to the electromagnetic core of Fig. 1. When a conductor 14 is to be wrapped with an insulating Sheet 15, the bar roller 18 is placed in the V-shaped groove and the coil slid under it as with the machine of Fig. 1. However, depending upon the amplitude of the magnetic force, it may be desirable to leave the bar roller 18 in the holder 17 until the coil form is positioned. While the force exerted by the permanent magnet cannot be conveniently dispclled by merely opening a switch, this structure is advantangeously employcd where utilization of an external energy source is not desired or feasible.

The end view of the machine of Pig. 4 corresponds to the machine of Pig. 3 except that the use of a straightsided bar 2d is illustrated in this case. Its generally rectangular cross section is rounded in the area of developing contact with the rotating coil form, and the fiat sides provide a larger surface contact and hence more pressure with respect to both the side 26 of the jig groove against which the bar slides and to the side of the coil being wound. The permanent magnet 27 therein is shown in an off-center position with respect to the apex of the V- shaped groove so that most of the magnetic pressure is exerted through the side 26 of the jig. Other variations in the pressure bar conformation may be made, of course, to accommodate either the Shape of the groove or of the conductor being wrapped.

Fig. 5 illustrates another V-shaped jig 23 made of a non-magnetic material such as brass and having iron or other magnetic material inserts 29 secured therein opposite the location of the pole faces of the magnet 30. To provide off-center magnetic force, the iron inserts may suitably be confined to one side of the iig 28. These iron inserts increase the holding power of a given magnet since the length of the low permeability portion of the fiux bar is greatly reduced or eliminated thereby. When the Wrapping bar is stored in the holder 28 where such inserts are employed in combination with the permanent magnet, the inserts together with the bar provide a keeper for the magnet.

It is obvious that, while the generally V-shaped groove has been shown in the jig embodiments illustrated herein, the groove may be generally rounded or the angle of the groove may be increased or decreased depending uporl the particular size of the coil to be wrapped. lt is further apparent that in each of the embodiments described, insulation particles and binding materials may be very easily removed from the jig since the wrapping bar can be easily lifted out.

While we have shown particular embodiments of our invention, it will be understood, of course, that we do not wish to be limited thereto since many modifications may be made, and we, therefore, aim by the appended claims to cover any such modifications as fall within the true spirit and scope of our invention.

What We claim as new and desire to secure by Letters Patent of the United States is:

1. A device for wrapping a conductor with insulating material and comprising a jig having a non-magnetic V- shaped member having inner surfaces large enough for accommodating a length of said conductor to be insulated and outer surfaces, a magnet means having pole pieces of opposite polarity adjacent to said outer surfaces of said jig, and a member of magnetic material arranged to be placed within said jig on said conductor and said insulating material in the field of said magnetic means for urging said insulating material against said conductor.

2. A device for Wrapping a conductor `with a sheet of insulating material and comprising a jig having a nonmagnetic V-shaped member having inner surfaces large enough for accommodating a length of said conductor to be insulated and an outer surface, a magnet means` having pole pieces of opposite polarity adjacent to said outer surface of said V-shaped section, and a roller of magnetic material arranged within said iig on said conductor and said insulating material in the field of magnet means for urging said insulation material against said conductor.

3. A device for wrapping a conductor with a sheet of insulating material and comprising a jig having a nonmagnetic V-shaped channel member having inner surfaces large enough for accommodating a length of said conductor to be insulated and an outer surface, a magnet means having pole pieces of opposite polarity postioned along the axis of and adjacent to said outer surface ot' said V-shaped section, and a roller of magnetic material adapted to be positioned within said jig on said conductor' and said insulating material in the field of said magnet means for urging said insulation material against saidl conductor.

4. A device for Wrapping a conductor with a sheet of insulating material and comprising a jig having an inner surface for supporting said conductor and said insulation material and having an axially uniform V-shaped member opening upward, an electromagnet having pole pieces of opposite polarity positioned along the axis of and adjacent to and below said V-shaped section, and a cylndrical roller of magnetic material adapted to be arranged within said jig on said conductor and said insulating material in the region of said magnet for urgng said insulation material against said conductor when current is applied to said electromagnet.

5. A device for Wrapping a straight portion of a U- shaped conductor with a sheet of insulating material and comprising a roller of magnetic material, a jig having a non-magnetic V-shaped channel portion for supporting said straight portion of a conductor, said insulation mate-7 rial and said roller during the wrapping operation, said channel portion having one side being extended and bent to form a concave shelf portion for supporting said roller during the loading and unloading Operations, and a magnet means having pole pieces of opposite polarity positioned along the axis of and adjacent to and below said channel portion so that said roller urges said insulation material against said conductor.

6. A wrapping machine for insulating a straight portion of a conductor assembly with an insulating Sheet without subjecting the Sheet to undue stress, comprising a horseshoe magnet having its poles extended upwardly, a bar of magnetic material, and a holding jig of nonmagnetic material bent along a lengthwise axis to provide two planar surfaces extending upward from said axis, said jig being secured to said magnet so that said poles are positioned along said axis of said jig, said jig being of a size suificient to accommodate the conductor assembly and said bar lying on top thereof while the conductor assembly is being rotated to wrap the sheet thereon.

7. A wrapping machine for insulating the straight side of a partially formed coil of a dynamoelectric machine with an insulating sheet without subjecting the sheet to undue stress, comprising a horseshoe permanent magnet having its poles extending upwardly, a bar roller made of magnetic material, said roller being of suflicient length to act as a keeper for said magnet, and a holding jig of nonmagnetic material bent along a lengthwise axis to provide two planar surfaces extending upward from said axis, said jig being secured to said magnet so that said poles are positioned along said axis of said jig, said jig being of a size sufiicient to accommodate the coil side With said bar roller lying on top thereof While the coil side is being rotated to wrap the Sheet thereon.

8. A wrapping machine for insulating the straight side of a partially formed coil turn of a dynamoelectric machine with an insulating sheet without subjecting the insulatng Sheet to undue stress, comprising a horseshoe electromagnet having its poles extending upwardly, a bar roller of magnetic material, said roller being of suicient length to carry flux between said poles, a holding jig of nonmagnetic material bent along a lengthwise axis to provide two planar surfaces extending upwardly from said axis, said jig being secured to said magnet with the poles of said magent adjacent to said axis, and said jig being of a size suflicient to accommodate 'the coil side with said bar roller lying on top thereof while the coil side is being rotated to wrap the sheet thereon.

9. A wrapping machine for insulating the straight side of a partially formed coil turn of a dynamoelectric machine with an insulating sheet without subjecting the sheet to undue stress, comprising a horseshoe permanent magnet having its poles extending upwardly, a bar made of magnetic material, said bar being of sufiicient length to act as a keeper for said magnet, a holding jig of nonmagnetic material bent along a lengthwise axis to provide two planar surfaces extending upward from said axis, said jig being secured to said magnet so that said poles are positioned along said axis of said jig, said jig being of a size suflicient to accommodate the coil side with said bar lying on top thereof while the coil side is being rotated to wrap the sheet thereon, and a pair of inserts of magnetic material placed in said jig in contact with said poles to increase the holding power of said magnet.

References Cited in the file of this patent UNITED STATES PATENTS 2,443,582 Lendo et al June 15, 1948 FOREIGN PATENTS 586,978 Great Britain Apr. 9, 1947 680,848 Great Britain Oct. 15, 1952 

1. A DEVICE FR WRAPPING A CONDUCTOR WITH INSULATING MATERIAL AND COMPRISING A JIG HAVING A NOON-MAGNETIC VSHAPED MEMBER HAVING INNER SURFACES LARGE ENOUGH FOR ACCMMODATING A LENGTH OF SAID CONDUCTOR TO BE INSULATED AND OUTER SURFACES, A MAGNET MEANS HAVING POLE PIECES OF OPPOSITE POLARITY ADJACENT TO SAID OUTER SURFACES OF SAID JIG, AND A MEMBER OF MAGNETIC MATERIAL ARRANGED TO BE PLACED WITHIN SAID JIG ON SAID CONDUCTOR AND SAID INSULATING MATERIAL IN THE FIELD OF AID MAGNETIC MEANS FOR URGING SAID INSULATING MATERIAL AGAINST SAID CONDUCTOR, 